a) An objective lens is used to couple free space light (red beam) into the microtoroid. The resonant scatter light is collected at the opposite edge as indicated by the orange beam. b) Scanning electron micrograph of a microtoroid resonator (SEM image). c) Microtoroid resonance wavelength at different temperatures. d) Resonance wavelength shift vs. temperature. A linear fit is shown as a solid black line. Image: Sartanee Suebka, Euan McLeod & Judith Su